5. The points of discharge of urban waste water shall be chosen, as far as possible, so as to minimise the effects on receiving waters.E+W
The values for concentration or for the percentage of reduction shall apply.
{s001} Reduction in relation to the load of the influent. {s002} The parameter can be replaced by another parameter: total organic carbon (TOC) or total oxygen demand (TOD) if a relationship can be established between BOD5 and the substitute parameter. | |||
Parameters | Concentration | Minimum percentage of reduction {s001} | Reference method of measurement |
---|---|---|---|
Biochemical oxygen demand (BOD5 at 20°C without nitrification {s002} | 25 mg/l O2 | 70—90 | Homogenized, unfiltered, undecanted sample. Determination of dissolved oxygen before and after five-day incubation at 20°+1°C, in complete darkness. Addition of a nitrification inhibitor |
Chemical oxygen demand (COD) | 125 mg/l O2 | 75 | Homogenized, unfiltered, undecanted sample Potassium dichromate |